In order to feed paper to processing devices such as document copier machines, it is frequently necessary to align the paper such that the side edge of the paper enters the processing station uniformly from piece to piece. In order to accomplish that alignment it is necessary to move the paper into the registering guide, but to do so without crumpling the edge of the paper. This has proved to be a fairly difficult problem, especially with very lightweight papers.
Prior art machines have typically used several different configurations of solid rollers in which the angle of the drive roller is set at a particular angle to provide a certain amount of referencing force relative to the drive force, i.e., as the paper was being moved forward the angle of the roller would also provide a force to move it sideways against the referencing edge. In the past it has been believed that the smaller the angle of the drive roller to the path the less the reference force as the paper is being driven down the paper path. As will be shown herein, this belief is faulty for the true reference edge force is a function of the drive force of the aligning roller and the resultant force vector of all forces that are applied to the sheet. Problems which prior art systems have encountered are that fairly high drive forces have been needed to move thick stock forwardly in order to counteract high drag forces, particularly when moving that stock around a bend. However, when moving thin paper drag forces are lower and the referencing force into the registering edge may be high and as a result the thin paper is crumpled. The typical problem of moving paper involves how does one align the sheet, provide a high drive force, and yet keep the referencing edge force low enough to not bend or damage the edge of the paper being referenced. It is, therefore, the object of this invention to provide alignment rollers which move the paper into a reference edge with a controlled force while maintaining sufficiently high drive forces to move all paper stocks in the drive direction without difficulty.